Scale prevention method by brine acidification with biochemical reactors

Siliceous scale deposition often causes serious problems in geothermal power stations. In order to solve these problems, a number of scale prevention methods have been proposed to date, one of which is brine acidification. Although it is well known that silica deposition is prevented by keeping the pH of the geothermal brine acidic, the pH adjustment of the brine by mineral acid injection has not been commercially applied so far in geothermal power stations. A new method is proposed in which sulfuric acid can be biochemically manufactured from hydrogen sulfide in the gas exhausted from geothermal power stations. The applicability of this method has been experimentally confirmed in field tests with a biochemical reactor. It is believed that the method will provide an economical and environmentally-friendly acidification process to prevent siliceous scale deposition and will also contribute to the reduction of hazardous hydrogen sulfide emission from geothermal power stations.